Circuit arrangement for charging or discharging condensers



1950 G. J. SIEZEN 2,507,226

' CIRCUIT ARRANGEMENT FOR CHARGING 0R DISCHARGING CONDENSERS Filed llay 5, 1947 2 Sheets-Sheet 1 E: 7 5E --V I T a JAN SREZ EN I NVENTOR ATTORNEY y 1950 G. J, SIEZEN 2,507,226

' CIRCUIT ARRANGBAENT FOR CHARGING OR DISCHARGING CONDENSERS Filed May 5, 1947 2 Shuts-Sheet 2 a. JAN sarazm EMVENTOR AT? QHMEY Patented May 9, 1950 CIRCUIT ARRANGEMENT FOR CHARGING R DISCHARGI'NG CONDENSERS Gerrit Jan Siezen, Eindhoven, Netherlands, as-

signor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application May 5, 1947, Serial No. 745,984 In the Netherlands June 17, 1946 Claims. (01. 320-1) 1 It is well-known that consequent on charging Fig. 7 is a circuit diagram showing a further or discharging a condenser much energy is genembodiment of the invention. erally wasted. If, for example, a condenser hav- Fig. 1 shows a circuit-arrangement for charging a capacity C is charged with the aid of a. ing a condenser I having a capacity C, which is direct current source having an output voltage connected in series with a coil 2 having an induc- E, the source of voltage and the condenser having tance L, a switch 3 and a battery 4 having an connected in between them any conductive ciroutput voltage E. Connected to this battery is cult-element, for example, a resistance, the elecalso a circuit which comprises the series comtrostatic energy accumulated in the condenser bination of a second coil 5 having an inductance upon termination of the charging process is nL (n 1) and arectifler 6. The currents, ii any, CE. However, during the charging process the passing through these circuits when the switch 3 source of voltage has supplied a total energy oi is closed are designated 1 and i0 respectively. The CE. so that an amount or energy of vs C131 is voltages are taken as positive, if their polarity wasted. In this connection it is mentioned that corresponds to that shown in the figure. this amount of dissipated energy is independent The sense in which coil 5 is wound is such that oi the nature of the circuit element. immediately on closing switch 3 the voltage V; The invention has for its obiectto provide a across the rectifier 6 is negative, so that initially method of charging or discharging a condenser, 110:0. Between the current i and the voltage V in which dissipation of energy is greatly reduced. across the condenser there is the relation:

The method according to the invention is charv acterized in that charging or discharging is i=c eil'ected for a quarter period of the natural oscillation set up in the series combination of the conso that denser and an inductance coil included in the di V charging or discharging circuit and in that the Ft F :15

energy accumulated in the inductance coil is then It f ll if regard is had to the mmal comm supplied to an energy accumulamrtions, that for the time t=0 V and i are also zero,

As will be set out more fully hereinafter, a that considerable part of the energy, which is otherv g (1 c5 t wise lost, for example, in the form of heat in a so in which resistance, is recovered by the use of the said method. In order that the invention may be more clearly V understood and carried into eifect, it will now be If th leakage inductance and the resistance of described more fully with reference to the acthe transformer formed by coils 2 and 5 are companying drawing, in which a number of emnegligible and if the coeflicient of reciprocal inbodiments oi circuit-arrangements for carrying du tan i M nL, the following relation also out the method according to the invention are applies:

illustrated. 40

Figure 1 is a schematic diagram showing one V.= embodiment of the invention;

Fig. 2 is a graphical representation of currents Thus voltage v Wm increase in accordance with and voltages existing in the circuit shown in Formula 1 attains the Value zero' This Fig. occurs for t=t1, 221 being determined by Fig. 3 is a schematic diagram showing a further n+ l embodiment of the invention; "T

Fig. 4 is a graphical representation of the curor rents and voltages existent in the circuit shown in Fig. 3; cos wt,=- (2) Fig. 5 is an embodiment of the invention showing the operation of the circuit for discharge; The Value which V attains is comequmfly Fig. 6 is a graphical representation of the curequal to rent and voltages existent in the circuit shown n+1 in Fig. 5; and

so that in the case of a high n the voltage exceeds the desired voltage E to a small extent only. This desired voltage was already attained before t=t1 at the end of the first quarter period of the oscillation set up.

As soon as the rectifier becomes conductive. For the sake of simplicity it is assumed that during the passage of the current in through the rectifier the voltage V; remains zero. which will be the case if the resistance of the rectifier is negligible. In this case in which it (h) designates the current in at the moment of time h.

The value of to (to follows from the continuity of the magnetic energy accumulated in the transformer as a function of time:

and hence nio (ti) =i (ti) As far as t1 we have according to (1) V=E (1-cos wt) hence i=wCE sin wt and from this together with (2) follows:

i(t )=ni (i )=wCEJ1 and this, combined with (3) The current in is zero from the moment of time t=0, at which the switch 3 is closed, to t:t1 at which mo abruptly jumps to the value wcn f 1 after which it decreases linearly until the value zero is attained at the moment of time t2.

The rectifier '6 then again becomes non-conductive and the excess of accumulated energy in the condenser will oscillate out with an initial amplitude of about the desired value E. If n is high, the energy thus lost is only a very small fraction of the energy accumulated in the condenser.

In Figs. 2a, 2b, 2c and 2d is plotted the variation of the values V, V i and nio respectively as a function of time, said variation being obvious with reference to the above calculation.

Fig. 2a shows that the condenser is charged up to the voltage E for a quarter period of the natural oscillation which is set up in the circuit of condenser l and coil 2 after switching on and that feeding back of the energy accumulated in the coil then starts at the moment of time iii. The quantity of fed back energy is l 1 tudi=ifiwcE (lg-t -\/1 from which, together with follows an amount which is increased as n is made smaller.

Fig. 3 shows a further circuit-arrangement for charging a condenser.

In this case the condenser 1 is also connected in series with a coil 8, a switch 9 and a source of direct current Ill. The series combination of a coil II and a rectifier I2 is connected in parallel with the condenser, the sense of winding of the coil again being such that initially after switching on the charging circuit the rectifier has no current in passing through it. The coil 8 exhibits an inductance L and the coil ll an inductance n L(n 1), the coefiicient of reciprocal inductance being M nL.

A calculation similar to that for the circuitarrangement of Fig. 1 again permits of the variations of the condenser voltage V, the voltage across the rectifier V,;, the current i in the condenser circuit and the current is in the rectifier circuit being calculated as a function of time. These variations are illustrated in Figs. 4a, 4b, 4c and 4d respectively. Fig. 4a shows that the condenser is charged in the first quarter period of the natural oscillation set up in the series combination of condenser I and coil 8 and that at the moment of time 131 feeding back of the energy is then started.

As shown by the circuit-arrangement and also by Figs. 4c and 4d, during the feed back of the energy, from t1 to t2, the current i0 passes through both coils 8 and II.

The energy fed back to the battery it] in this circuit-arrangement is found to be equal to an amount which consequently also increases as n is increased.

At the moment of time its the rectifier l2 again becomes non-conductive and the circuit 1, 8 oscillates out with an initial amplitude of about the ultimate value -E, little energy again being lost, if n is large.

Fig. 5 shows a circuit-arrangement which permits of feeding back to a battery substantially entirely the energy released on the discharge of a condenser by short-circuiting.

In this case a condenser l8 exhibiting a capacity C is connected in series with a coil M exhibiting an inductance L, and switch I 5. Condenser I3 is charged from a direct current source I! through a resistor ll. There is also a circuit constituted by the series combination of a coil ll having an inductance n'L (n 1), a rectifier l1 and direct current source ll having an output voltage E. The lower ends of coil I4 and coil I are connected together. The coil I6 is wound in such manner that after switch I! is closed the rectifier has initially no current passing through it. In this case the coeillclent of reciprocal inductance of the coils l4 and l! is M=-nL. The voltage across the condenser decreases from the initial value V=+E at the moment of time t= until t=t1 according to V=E 008 out with 1 al -T,

At t=t1, when the rectifier becomes conductive, after which remains constant, whereas i becomes zero. Energy is then fed back to the battery during the interval t1 t t2.

By way of further illustration of the operation of the circuit-arrangement, Figs. 6a, 6b, 6c and 6d show the variations of the condenser voltage V, of the voltage V; across the rectifier, the current i in the discharge circuit and the current in multiplied by n passing through the rectifier as a function of time.

A circuit-arrangement of the type shown in Fig. permits of materially increasing the efficiency of a time base generator. A circuit-arrangement for this purpose is shown in Fig. '7, in which those parts which are similar to those of Fig. 5 have equal reference numerals, a gasfilled triode being, however, substituted for the switch ii of Fig. 5. A properly chosen control-voltage may be fed to the control grid of this tube via terminals 22 and 23' from a bias voltage source 2!, but in the circuit-arrangement described hereinafter use is not made of a control-voltage and the tube 20 becomes conductive as soon as a given anode voltage is attained.

The energy released on the discharge of condenser I3 is supplied to the battery It. This battery now also ensures, via a resistance l9 having a value R, that the condenser is charged.

If the condenser is charged through the resistance l9 up to a voltage Vb, at which tube 20 ignited, the electrostatic energy accumulated in the condenser first passes into coil l4, so that the voltage V across the condenser falls to a value which is approximately equal to the arc voltage of tube 20, whereas the current i is increased to a maximum value which is approximately equal to wCVb. ii

The rectifying tube I! then becomes conductive and the value of the current i abruptly jumps to zero, so that the gasfilled triode 20 is extinguished. The energy accumulated in the transformer at that moment of time, which energy is approximately equal to /2CVi, is then substantially entirely fed back to the battery through the diode II.

Beyond a lower energy consumption this circuit-arrangement has the advantage that the moment of time at which the gas-filled triode is extinguished is very sharply defined as against the moment of time at which ignition takes place, which is very important, for example if used in circuit-arrangements for television purposes.

The fiy-back time o! the saw-tooth voltage set up across the condenser is limited by the maximum permissible current strength in through the gasfilled triode 20. In the present case, the dyback time T is equal to one quarter of the period of the natural oscillation of the LC-circuit ll. ll; consequently The maximum current im becomes, as already indicated above, im=wCVb so that It a condenser having a capacity C is discharged through a resistance R0, the fly-back time will be at least twice the time constant M. consequently T22R00 and since in this case V CV Eur-F0" At the same values for irn, C and Vb the circuitarrangement shown in Fig. '7 consequently also exhibits the advantage of a smaller fly-back time.

What I claim is:

1. A circuit arrangement for producing charge variations in a condenser, comprising in series circuit arrangement a switch member, said condenser and an inductor, a source of direct current, means to couple said series circuit to said source, a unidirectional conductor poled in opposition to said source, and an inductive element magnetically linked to said inductor and connected in series with the said unidirectional conductor and said current source.

2. A circuit arrangement for producing charge variations in a condenser, comprising a source of direct current, a first series circuit connected in shunt with said source and comprising a first inductive element, said condenser and switching means to produce current flow through said condenser and said inductance element, and a second series circuit connected in shunt with said source and comprising a rectifier poled in opposition to said source and a second inductive element magnetically linked to said first inductive element.

3. A circuit arrangement for producing charge variations in a condenser, comprising a direct current source, a first circuit comprising in series connection a first inductive element, said condenser and a gaseous discharge tube, means to couple said first circuit to said source, and a second circuit connected in shunt with said source and comprising in series connection a rectifier poled in opposition to said source and a second inductive element magnetically linked to said first inductive element.

4. A circuit arrangement for producing charge variations in a condenser, comprising a direct current source, a resistance element connecting said condenser to said source, a first circuit comprising in series connection a first inductive element, said condenser and a discharge tube having a control grid, and a second circuit connected in shunt with said source and comprising in series connection a rectifier poled in opposition to said source and a second inductive element magnetically linked to said first inductive element, said first and second inductive elements being so poled relative to each other that the polarity of the voltage initially induced in said second inductive element upon initial current flow through said first inductive element and said discharge tube is in opposition to the polarity of said rectifier. GERRIT JAN SIEZEN.

8 REFERENCES mm Number UNITED STATES PATENTS Name Date Knowles et a1 June 29, 1987 Haine May 14, 1946 

